This invention relates to a lightweight folding bicycle, particularly to the improvment on the structure of normal folding bicycle.
A shockproof foldable bicycle is disclosed in China Patent No.902074636. Its folding structure is with two seat tubes in front and back, their buttom ends hinge joint with the tail end of a crossbar respectively and the bottom end of the back crossbar joints a back fork simultaneously. The other end of the back fork joints a flat fork and the other end of the flat fork joints a standing tube and a down tube at the same point. The other end of the standing tube joints in the middle of the front seat tube and the other end of the down tube joints in the middle of the crossbar. The siting of the bike while unfolded is realized by a bidirectional-interlocking-device mounted in the tail end of the crossbar. A wedge clip on the knob of the bidirectional-interlocking-device embed on the sunken of the front seat tube bottom end to prevent the front seat tube rotating around an axle, so as to site the frame. Because the sunken in the bottom end of the front seat is near the axle while a saddle fixed on the top of the front seat tube is far from the axle and the seat tube leans back, the saddle endures weakly. Besides, the surface of the wedge clip is easy to be worn and then produce gap, it will bring some hidden danger to rider. A pedal has no folding device. A folding device of a handlebar stem is fixed by screws. This type of folding bicycle has a complicated structure and cannot be handled easily. It is also high cost, heavy weight, less loaded and the saftey of use cannot be insured.